A variety of hormones, neurotransmitters and biologically active substances control, regulate or adjust the functions of living bodies via specific receptors located in cell membranes. Many of these receptors mediate the transmission of intracellular signals by activating guanine nucleotide-binding proteins (G proteins) to which the receptor is coupled. Such receptors are generically referred to as G-protein coupled receptors (GPCRs) and include, among others, α-adrenergic receptors, β-adrenergic receptors, opioid receptors, cannabinoid receptors and prostaglandin receptors. The biological effects of activating or inhibiting these receptors is not direct but is mediated by a host of intracellular proteins. The importance of these secondary proteins has only recently been recognized and investigated as potential intervention points in disease states. One of the most important classes of these downstream effectors is the “kinase” class.
The various kinases thus play important roles in the regulation of various physiological functions. For example, kinases have been implicated in a number of disease states, including, but not limited to: cardiac indications such as angina pectoris, essential hypertension, myocardial infarction, supraventricular and ventricular arrhythmias, congestive heart failure, atherosclerosis, renal failure, diabetes, respiratory indications such as asthma, chronic bronchitis, bronchospasm, emphysema, airway obstruction, upper respiratory indications such as rhinitis, seasonal allergies, inflammatory disease, inflammation in response to injury, rheumatoid arthritis. The importance of p38 MAPK inhibitors in particular as new drugs for rheumatoid arthritis is reflected by the large number of compounds that has been developed over the last years (J. Westra and P. C. Limburg Mini-Reviews in Medicinal Chemistry Volume 6, Number 8, August 2006). Other conditions include chronic inflammatory bowel disease, glaucoma, hypergastrinemia, gastrointestinal indications such as acid/peptic disorder, erosive esophagitis, gastrointestinal hypersecretion, mastocytosis, gastrointestinal reflux, peptic ulcer, Zollinger-Ellison syndrome, pain, obesity, bulimia nervosa, depression, obsessive-compulsive disorder, organ malformations (e.g., cardiac malformations), neurodegenerative diseases such as Parkinson's Disease and Alzheimer's Disease, multiple sclerosis, Epstein-Barr infection and cancer (Nature Reviews Drug Discovery 2002, 1: 493-502). In other disease states, the role of kinases is only now becoming clear. The retina is a complex tissue composed of multiple interconnected cell layers, highly specialized for transforming light and color into electrical signals that are perceived by the brain. Damage or death of the primary light-sensing cells, the photoreceptors, results in devastating effects on vision. Despite the identification of numerous mutations that cause inherited retinal degenerations, the cellular and molecular mechanisms leading from the primary mutations to photoreceptor apoptosis are not well understood, but may involve the wnt pathway (A S Hackam “The Wnt Signaling Pathway in Retinal Degeneration” IUBMB Life Volume 57, Number 6/June 2005).
The success of the tyrosine-kinase inhibitor STI571 (Gleevec) in the treatment of chronic myelogenous leukaemia (Nature Reviews Drug Discovery 2003, 2: 296-313) has spurred considerable efforts to develop other kinase inhibitors for the treatment of a wide range of other cancers (Nature Reviews Cancer 2003, 3: 650-665). The balance between the initiation and the inactivation of intracellular signals determines the intensity and duration of the response of the receptors to stimuli such as agonists. When desensitization occurs, the mediation or regulation of the physiological function mediated or regulated by the G proteins to which the receptors are coupled is reduced or prevented. For example, when agonists are administered to treat a disease or condition by activation of certain receptors, the receptors relatively quickly become desensitized from the action of the GRKs such that agonist administration may no longer result in therapeutic activation of the appropriate receptors. At that point, administration of the agonist no longer enables sufficient or effective control of or influence on the disease or condition intended to be treated.
In view of the role that kinases have in many disease states, there is an urgent and continuing need for small molecule ligands which inhibit or modulate the activity of kinases. Without wishing to be bound by theory, it is thought that modulation of the activity of kinases by the compounds of the present invention is, at least in part, responsible for their beneficial effects.